US4083244A - Method and apparatus for measuring fluid flow and/or for exercising a control in dependence thereon - Google Patents
Method and apparatus for measuring fluid flow and/or for exercising a control in dependence thereon Download PDFInfo
- Publication number
- US4083244A US4083244A US05/743,029 US74302976A US4083244A US 4083244 A US4083244 A US 4083244A US 74302976 A US74302976 A US 74302976A US 4083244 A US4083244 A US 4083244A
- Authority
- US
- United States
- Prior art keywords
- heat
- conduit
- flow
- emitting members
- fluid flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/696—Circuits therefor, e.g. constant-current flow meters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/696—Circuits therefor, e.g. constant-current flow meters
- G01F1/698—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
Definitions
- This invention concerns apparatus for determining fluid flow and/or for exercising a control in dependence thereon.
- ⁇ T the temperature differential between the hot body and the fluid
- V THE FLOW VELOCITY OF THE FLUID
- M the mass flow of the fluid.
- the heat loss depends upon the temperature differential ⁇ T and upon various properties of the fluid being measured, i.e. the fluid conductivity K, the fluid density ⁇ and the fluid viscosity ⁇ . Consequently, the mass flow, if deduced from the heat loss, also depends upon these factors.
- ⁇ (G) a function of the Grashof number of the body, ##EQU2##
- T the absolute temperature of the hot body.
- the arrangement also may in certain circumstances, have undesirable thermal equilibrium properties.
- apparatus for determining fluid flow and/or exercising a control in dependence thereon, said apparatus comprising flow obstruction means and two heat-emitting members which are mounted in a geometrically symmetrical arrangement in a conduit so that the heat-emitting members are subject to the same heat loss when there is no fluid flow through the conduit, the flow obstruction means causing the two heat-emitting members to be differently affected by the fluid flow through the conduit, and means responsive to the ratio of the heat losses from the two heat-emitting members for determining the said fluid flow and/or for exercising a control in dependence thereon.
- the fluid flow is determined, and/or the control is exercised, in dependence upon the ratio of the heat losses from the two heat-emitting members, and consequently the zero shift problem which is referred to above is eliminated since both of the heat-emitting members are equally affected by natural convection. Moreover, since both the heat-emitting members are subject to the fluid flow and operate under the same mode of heat loss by forced convection, compensation is better than is given by the use of a reference hot body in a cavity operating under natural convection.
- the apparatus of the present invention is sensitive to the flow direction.
- the conduit may, if desired, be a by-pass conduit which is arranged to receive part of the flow passing through a duct.
- the conduit may be provided in a probe which is adapted to be inserted into a duct.
- the flow obstruction means may comprise a flow obstruction member on opposite sides of which the heat-emitting members are disposed
- the heat-emitting members may be disposed on opposite sides of and are aligned with an orifice in a flow obstruction member which extends completely across the conduit.
- the heat-emitting members may be disposed on opposite sides of a flow obstruction member which extends partially across the conduit.
- heat-emitting members are located at opposite ends of a venturi-shaped flow obstruction means.
- the flow obstruction means comprises two flow obstruction members which are spaced apart along the axis of the conduit, the heat-emitting members being disposed between the two flow obstruction members.
- Means are preferably provided for heating the heat-emitting members.
- the heat-emitting members may be thermistors, hot wire anomometers or thermocouples.
- the invention also comprises a method of determining the fluid flow through a conduit and/or for exercising a control in dependence thereon, said method comprising mounting flow obstruction means and two heat-emitting members in a geometrically symmetrical arrangement in the conduit so that the heat-emitting members are subject to the same heat losses when there is no fluid flow through the conduit, producing a fluid flow through the conduit which causes the two heat-emitting members to be differentially affected by the said fluid flow, and employing the ratio of the heat-losses from the two heat-emitting members to determine the said fluid flow and/or to exercise the said control.
- the said ratio may be employed to determine the direction of flow of the fluid through the conduit.
- FIGS. 1 to 5 are broken-away diagrammatic views of a number of different embodiments of apparatus according to the present invention.
- FIGS. 6 and 7 are broken-away diagrammatic views of further embodiments of apparatus according to the present invention each of which incorporates a by-pass,
- FIG. 8 is a circuit diagram
- FIG. 9 is a diagrammatic view of a probe incorporating apparatus according to the present invention and inserted into a duct,
- FIGS. 10 and 11 are diagrammatic views of two different probes each having a by-pass conduit in which the apparatus of the present invention is provided, and
- FIG. 12 is a diagrammatic broken away perspective view of a flue stack provided with apparatus according to the present invention.
- FIG. 1 there is shown a conduit 10 within which is mounted a flow obstruction member or orifice plate 11 which extends transversely of and completely across the conduit 10, the orifice plate 11 having a centrally disposed orifice 12 therein.
- thermistors, or other heat-emitting members 13, 14 which are equally spaced from the orifice plate 11, and which are aligned with the orifice 12 therein.
- the orifice plate 11 and the thermistors 13, 14 are thus disposed in a geometrically symmetrical arrangement having a plane of symmetry extending transversely of the conduit 10 and centrally through the orifice plate 11, such a symmetrical arrangement ensuring that the thermistors 13, 14 have the same heat losses at zero flow therepast.
- the thermistors 13, 14 are, so to speak, assymmetrical with respect to the fluid flow through the conduit 10, since the thermistor 13 is subjected to a fluid flow which is substantially unaffected by the existence of the orifice plate 11, while the thermistor 14 is subjected to the jet issuing through the orifice 12.
- the orifice plate 11 thus causes the thermistors 13, 14 which are heated by means not shown, to be differentially affected by the fluid flow through the conduit 10, so as to have different heat losses.
- the ratio of the outputs from the thermistors 13, 14 is used to produce an indication of the flow rate.
- This use of the said ratio ensures that there is no change in the indication of the flow rate irrespective of the temperature difference between the thermistors 13, 14 and the fluid passing through the conduit 10 and irrespective of the thermal conductivity of said fluid.
- the use of the said ratio, together with appropriate design of the thermistors 13, 14, also eliminates any effect on the said indication by the density or pressure of the fluid.
- V 13 and V 14 are the voltages across the thermistors 13,14 respectively.
- ⁇ T the temperature difference between the thermistors 13,14 and the gas
- M the mass flow rate in kg/m 3 .
- K the thermal conductivity of the gas.
- FIG. 1 provides a high output because of the jet effect, and enables one to tune the apparatus by varying the size of the pipe, the size or shape of the jet, and the size or spacing of the thermistors 13, 14. It is, moreover, simple to manufacture, and, when used in a by-pass as shown in any of FIGS. 6, 7, 10 and 11, determines the by-pass flow.
- FIGS. 2 to 5 are generally similar to that of FIG. 1, and will not therefore be described in detail, like reference numerals indicating like parts.
- the orifice plate 11 is replaced by a venturi-shaped flow obstruction member 15 having a throat 16, the thermistors 13, 14 being located at opposite ends of the obstruction member 15.
- the thermistor 13 is disposed upstream of the throat 16, while the thermistor 14 is disposed downstream thereof and in the jet issuing from the throat 16.
- the orifice plate 11 of FIG. 1 is replaced by a flow obstruction member 17 which is rectangular in cross section and which extends only partially across the conduit 10, so as to leave a space 18 through which the fluid can flow.
- the thermistor 13 is disposed in the full flow of the fluid through the conduit 10, whereas the thermistor 14 is disposed in the wake of the obstruction member 17.
- FIG. 4 construction is generally similar to that of FIG. 3 except that, instead of providing a flow of obstruction member 17 which is rectangular in cross-section, a flow obstruction member 20 is provided which is triangular in cross-section.
- FIG. 5 construction use is made of two flow obstruction members 21, 22 which are spaced apart axially of the conduit 10 and each of which is substantially triangular in cross-section.
- the thermistors 13, 14 are disposed between the flow obstruction members 21, 22.
- the thermistor 13 is disposed in the wake of the flow obstruction member 21, while the thermistor 14 is disposed immediately upstream of the flow obstruction member 22.
- FIG. 1 or the FIG. 3 construction is employed for measuring a dirty flow of gas, it may be necessary to provide for filtration so as to ensure that the orifice 12 or space 18 does not become blocked. If such filtration is not for some reason practicable, or if it is wished to avoid the need to provide it, a construction as shown in any of FIGS. 2, 4 and 5 can be employed, since the shapes of the flow obstructions therein are such as to be much less subject to blockage by dirt.
- FIG. 6 construction is generally similar to that of FIG. 1 except that the orifice plate 11 and thermistors 13, 14 are arranged in a by-pass 19 which extends between opposite sides of an orifice plate 23; or other differential pressure device, in the conduit 10.
- FIG. 7 construction is similar to that of FIG. 6 except that the upstream end of the by-pass 19 is disposed immediately upstream of a venturi portion 24 while the downstream end of the by-pass 19 communicates with the throat of the venturi portion 24.
- the apparatus will be sensitive to the flow direction.
- the thermistor 14 will be subjected to a fluid flow which is substantially unaffected by the existence of the orifice plate 11, while the thermistor 13 will be subjected to the jet which will issue through the orifice 12.
- FIG. 7 construction is intended for use only for a fluid flowing in the direction of the arrow therein.
- the by-pass 19 instead of communicating with the throat of the venturi portion 24, is arranged (as indicated by dotted lines in FIG. 7) so that the opposite ends of the by-pass 19 are disposed symmetrically of the venturi portion 24, then the FIG. 7 construction can be used to measure flow in either direction.
- the thermistor 13 together with a Zener diode 25 constituting a safety barrier, is connected in one arm of an electrical bridge 26.
- the remaining arms of the bridge 26 have fixed resistances 27, 28, and a variable resistance 29.
- the voltages V 1 ' and V 1 " at points 30, 31 on the bridge 26 will be the same.
- the points 30, 31 are respectively connected to positive and negative terminals of a difference amplifier 32 the input to which is not shown.
- the output from the difference amplitude 32 is taken to a point 33 on a lead 34, the latter being connected to a point 35 on the bridge 26.
- the output voltage at the points 33, 35 will be reduced or increased respectively in such a way as, in practice, to maintain the temperature of the thermistor 13 substantially constant.
- an alteration in the heat dissipation of the thermistor 13 produced by a change in the flow rate or by a change in the temperature or composition of the fluid will produce a change in the voltage at the points 33, 35.
- the thermistor 14, together with a Zener diode safety barrier 36, is connected in one arm of an electrical bridge 37.
- the other arms of the bridge 37 respectively contain fixed resistances 40, 41 and a variable resistance 42.
- the voltages V 2 ' and V 2 " at points 43, 44 respectively on the bridge 47 are the same.
- the points 43, 44 are connected respectively to positive and negative terminals of a difference amplifier 45 the input to which is not shown and the output from which is connected at a point 46 to a lead 47, the latter being connected to a point 48 on the bridge 37.
- the thermistor 14 is kept at a constant temperature, any change in the heat dissipation of the thermistor 14 produced by variation in the temperature or composition of the gases flowing through the conduit 10 resulting in a change in voltage at the points 46, 48.
- the point 46 is connected to a transistor Q4 by a lead 49, a point 50 on which is connected to an integrator LA5 across which there is connected a circuit comprising a condenser C7 and resistance R23.
- the point 46 is connected to the integrator LA5 by a lead 46a containing a resistance R16, the lead 46a being connected by way of a resistance R18 to a transistor Q3 which is itself connected by way of a diode D6 to the output of a comparator LA6.
- the transistor Q3 is also connected through a diode D7 to the transistor Q4.
- the comparator LA6 is connected to the integrator LA5, the transistor Q4, and to a transistor Q5.
- the transistor Q5 is connected, by way of a resistance R34 and a diode D18, to the output of the comparator LA6.
- the circuit described in the preceding paragraph is a voltage to frequency converter circuit, such that, if the voltages at the points 33, 46 are V r and V f respectively, the output frequency F from the comparator LA6 is
- K is a variable which is adjustable by means not shown.
- the said voltage to frequency converter circuit operates as follows.
- the reference voltage of the comparator LA6 is set by the transistor Q4 at a value equal to Vr/2 when the output from the comparator LA6 is low, and is set by the transistor Q5 at a value equal to V r when the output from the comparator LA6 is high.
- the transistor Q3 is on and the output voltage of the integrator LA5 increases until it reaches the value V r .
- the output of the comparator LA6 then decreases, turning the transistor Q3 off and causing the output voltage of the integrator LA5 to decrease.
- the comparator LA6 switches over, thus reversing the direction of the integration, and the cycle repeats.
- the integration rate is set by the ratio of the values of the resistance R16 and R18 so as to be equal in both parts of the cycle.
- the output from the comparator LA6 is fed to a linearisation circuit 55 and thence via an amplifier 56 to an output display 57.
- any variation in the flow rate in the conduit 10 will produce a linear change at the output display 57.
- the circuit shown in FIG. 8 is designed to take account of the fact that the thermistors 13, 14 have only one stable operating point, and are automatically taken to this point during the initial warm-up time when the circuit is switched on.
- the output from the amplifier 56 instead of, or in addition to, being displayed at the output display 57 may be taken to a flow control valve 63 which controls, by means not shown, the amount of steam or other fluid to be mixed with gas flowing through the conduit 10.
- the conduit 10 may be a conduit through which waste gas flows to a flare stack (not shown), the amount of steam injected being controlled by the flow control valve 63, and being proportional to both the mass flow and molecular weight of the waste gas.
- conduit 10, thermistors 13, 14, and orifice plate 11 of the FIG. 1 construction are embodied in a probe 64 which is adapted to be inserted as shown in a gas duct 65.
- the thermistors 13, 14 and the orifice plate 11 of the FIG. 1 construction are provided in a by-pass conduit 66 which is formed in a probe 67, the by-pass conduit 66 having an upstream portion 68 which receives gases flowing through a gas duct 70, and a downstream portion 71 which returns the by-pass flow to the duct 70.
- the advantage of the construction shown in FIG. 10 is that the probe 67 can be provided with means (not shown) for removing dirt and moisture, for reducing heat, and for purging the by-pass conduit 66 of dirt, without the need to provide the gas duct 70 itself with any such equipment. In other words, only a very small proportion of the gases flowing through the gas duct 70 needs to be treated, e.g. by having dirt removed therefrom.
- FIG. 11 there is shown a construction for use in measuring low flows which is generally similar to that of FIG. 10.
- a probe 72 is employed having a plurality (e.g. four as shown) of inlet ports 73 each of which communicates with the upstream portion 68 of the by-pass conduit 66.
- the inlet ports 73 are spaced from each other in accordance with known approximation functions (e.g. those of Pade, Chebyschef, or Butterworth) such that the gas passing the thermistors 13, 14 in the by-pass conduit 66 has a composition corresponding to the average composition of the gas flowing through the whole gas duct 70.
- the probe 72 has a plurality (e.g. two as shown) of outlet ports 74 each of which communicates with the downstream portion 71 of the by-pass conduit 66, the use of such a plurality of outlet ports 74 preventing blocking in the event of reverse flow.
- the probe 72 is provided internally with welded blocks 75 (only one shown) so shaped as to force the gas which flows through the gas duct 70 in the direction of arrows 76 to enter the inlet ports 73 and to flow through the by-pass conduit 66 and so out through the outlet ports 74.
- the probe 72 is to be used to examine flows both in the direction of the arrows 76 and in the opposite direction, the probe 72 is provided with equal numbers of inlet ports 73 and outlet ports 74, and the inlet and outlet ports are aligned with each other.
- the probe 72 may be used for the examination of gas flowing through a duct of any shape, e.g. a cylindrical duct or one having a rectangular cross-section.
- the probe 72 is particularly suited, however, for examination of the gas flowing through a flue stack 80, as shown in FIG. 12.
- the portion of the by-pass conduit 66 which is disposed externally of the flue stack 80 may be provided as shown with a moisture trap 81 having a continuously self-draining "S" tube 82.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Measuring Volume Flow (AREA)
- Indicating Or Recording The Presence, Absence, Or Direction Of Movement (AREA)
- Flow Control (AREA)
Abstract
Description
Q.sub.F = K.ΔT φ (Re),
Δv.sub.1 = v.sub.13 - v.sub.14 = kmΔt.sub.1 - kgΔt.sub.1 = Δt.sub.1 k (m-g);
Δv.sub.2 = v.sub.13 - v.sub.14 = Δt.sub.2 k (m-g).
F = V.sub.f /V.sub.r + K,
Claims (14)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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UK48186/75 | 1975-11-24 | ||
GB48186/75A GB1512290A (en) | 1975-11-24 | 1975-11-24 | Method and apparatus for determining fluid flow rate and/or for exercising a control in dependence thereon |
Publications (1)
Publication Number | Publication Date |
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US4083244A true US4083244A (en) | 1978-04-11 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US05/743,029 Expired - Lifetime US4083244A (en) | 1975-11-24 | 1976-11-18 | Method and apparatus for measuring fluid flow and/or for exercising a control in dependence thereon |
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Country | Link |
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US (1) | US4083244A (en) |
JP (1) | JPS5265485A (en) |
DE (1) | DE2653359A1 (en) |
GB (1) | GB1512290A (en) |
Cited By (43)
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US4199981A (en) * | 1977-02-16 | 1980-04-29 | Wen Young | Flow control device for fluids flowing in a closed conduit |
EP0024327A1 (en) * | 1979-08-16 | 1981-03-04 | Rico Gesellschaft für Mikroelektronik mbH | Respirometer for measuring the respiratory flow rate and direction |
US4317365A (en) * | 1979-01-04 | 1982-03-02 | Robert Bosch Gmbh | Apparatus for the measurement of the mass of a flowing medium |
US4373387A (en) * | 1979-07-24 | 1983-02-15 | Hitachi, Ltd. | Air flow meter |
US4448064A (en) * | 1980-11-28 | 1984-05-15 | Mitsubishi Denki Kabushiki Kaisha | Device for detecting the intake air flow rate in an internal combustion engine |
US4461173A (en) * | 1982-05-17 | 1984-07-24 | Sierra Instruments, Inc. | Multirange flowmeter |
US4476720A (en) * | 1982-06-14 | 1984-10-16 | Cambridge Aero Instruments, Inc. | Unidirectional fluidflow sensor system |
US4587842A (en) * | 1982-12-30 | 1986-05-13 | Robert Bosch Gmbh | Arrangement for measuring the mass flow-rate of a flowing medium |
US4609912A (en) * | 1983-02-14 | 1986-09-02 | Ryan Stewart R | Detector system for detecting air infiltration leaks and the like |
US4653321A (en) * | 1985-06-07 | 1987-03-31 | Enron Corp. | Method of automatically measuring fluid flow rates |
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US4779458A (en) * | 1986-12-29 | 1988-10-25 | Mawardi Osman K | Flow sensor |
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US4317365A (en) * | 1979-01-04 | 1982-03-02 | Robert Bosch Gmbh | Apparatus for the measurement of the mass of a flowing medium |
US4403506A (en) * | 1979-01-04 | 1983-09-13 | Robert Bosch Gmbh | Apparatus for the measurement of the mass of a flowing medium |
US4373387A (en) * | 1979-07-24 | 1983-02-15 | Hitachi, Ltd. | Air flow meter |
EP0024327A1 (en) * | 1979-08-16 | 1981-03-04 | Rico Gesellschaft für Mikroelektronik mbH | Respirometer for measuring the respiratory flow rate and direction |
US4448064A (en) * | 1980-11-28 | 1984-05-15 | Mitsubishi Denki Kabushiki Kaisha | Device for detecting the intake air flow rate in an internal combustion engine |
US4461173A (en) * | 1982-05-17 | 1984-07-24 | Sierra Instruments, Inc. | Multirange flowmeter |
US4476720A (en) * | 1982-06-14 | 1984-10-16 | Cambridge Aero Instruments, Inc. | Unidirectional fluidflow sensor system |
US4587842A (en) * | 1982-12-30 | 1986-05-13 | Robert Bosch Gmbh | Arrangement for measuring the mass flow-rate of a flowing medium |
US4609912A (en) * | 1983-02-14 | 1986-09-02 | Ryan Stewart R | Detector system for detecting air infiltration leaks and the like |
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US4653321A (en) * | 1985-06-07 | 1987-03-31 | Enron Corp. | Method of automatically measuring fluid flow rates |
WO1988002819A1 (en) * | 1986-10-17 | 1988-04-21 | Andros Analyzers Incorporated | Detecting method and apparatus using heat sensitive devices |
US4756670A (en) * | 1986-10-17 | 1988-07-12 | Andros Analyzers Incorporated | Detecting method and apparatus using heat sensitive devices |
US4841938A (en) * | 1986-11-04 | 1989-06-27 | Vdo Adolf Schindling Ag | Device for determining the direction of flow |
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DE3935778A1 (en) * | 1989-10-27 | 1990-10-31 | Daimler Benz Ag | Mass measurer for flowing medium - has hot film air mass measurer with two hot films in flow measuring pipe esp. for intake air of IC engine in motor vehicle |
US5261272A (en) * | 1989-11-06 | 1993-11-16 | General Motors Corporation | Temperature sensor for integrated induction system |
US5000039A (en) * | 1989-11-21 | 1991-03-19 | Siemens-Bendix Automotive Electronics L.P. | Mass air flow integrator |
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EP0807202A1 (en) * | 1995-02-02 | 1997-11-19 | Mobil Oil Corporation | Method of monitoring fluids entering a wellbore |
EP0807202A4 (en) * | 1995-02-02 | 1999-12-22 | Mobil Oil Corp | Method of monitoring fluids entering a wellbore |
DE19618520C1 (en) * | 1996-05-08 | 1997-09-18 | Franz Willam | Flowmeter for respired air |
WO2001018496A2 (en) * | 1999-09-03 | 2001-03-15 | Microbridge Technologies Inc. | Several gas flow measuring devices and signal processing methods |
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US6702545B2 (en) * | 2002-05-01 | 2004-03-09 | Sanford Davis Scholten | Venturi fan |
US20050145007A1 (en) * | 2003-08-14 | 2005-07-07 | Wible Eric J. | Flowmeter in-situ calibration verification system |
US7191645B2 (en) * | 2003-08-14 | 2007-03-20 | Fluid Components International Llc | Dynamic mixed gas flowmeter |
US7201033B2 (en) * | 2003-08-14 | 2007-04-10 | Fluid Components International Llc | Flowmeter in-situ calibration verification system |
US20050034532A1 (en) * | 2003-08-14 | 2005-02-17 | Wible Eric J. | Dynamic mixed gas flowmeter |
US20050229717A1 (en) * | 2004-04-06 | 2005-10-20 | Byong-Jo Yun | Average bidirectional flow tube |
US7089805B2 (en) * | 2004-04-06 | 2006-08-15 | Korea Atomic Energy Research Institute | Average bidirectional flow tube |
US20090126507A1 (en) * | 2005-06-09 | 2009-05-21 | Siemens Vdo Automotive Ag | Flow sensor |
US7681461B2 (en) | 2006-09-06 | 2010-03-23 | Amir Rosenbaum | Pipe adapter for adjusting the flow past a sensor |
US20090077967A1 (en) * | 2007-09-25 | 2009-03-26 | Ford Global Technologies, Llc | High Flow (Delta P) Differential Pressure EGR System with Provision for Both Flow Control and OBD Monitor |
US7938105B2 (en) * | 2007-09-25 | 2011-05-10 | Ford Global Technologies, Llc | High flow (delta P) differential pressure EGR system with provision for both flow control and OBD monitor |
US20100031737A1 (en) * | 2008-08-11 | 2010-02-11 | Hitachi Automotive Systems, Ltd. | Mass air flow measurement device |
US8091413B2 (en) * | 2008-08-11 | 2012-01-10 | Hitachi Automotive Systems, Ltd. | Mass air flow measurement device |
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Also Published As
Publication number | Publication date |
---|---|
GB1512290A (en) | 1978-06-01 |
JPS5520193B2 (en) | 1980-05-31 |
JPS5265485A (en) | 1977-05-30 |
DE2653359A1 (en) | 1977-05-26 |
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